I use speedtest.com. Often I cannot connect to WiFi. However my wife's iPhone 17 Max (bought at the same time in October 2025) has no problem. If both phones connect to the same WiFi, her phone usually has a faster upload and download speed.
iPhone 17, iOS 26
By chance, do you have a VPN on your iPhone? If you do, DUMP it. VPNs cause all sorts of connectivity issues on iPhone. Open Settings > General > VPN & Device Management - Remove any VPN profile you have. Then remove any associated VPN app and restart your iPhone. Anti-Virus software can cause the same connectivity issues and are absolutely worthless on an iPhone, so if you have one, get rid of it as well.
By chance, do you have a VPN on your iPhone? If you do, DUMP it. VPNs cause all sorts of connectivity issues on iPhone. Open Settings > General > VPN & Device Management - Remove any VPN profile you have. Then remove any associated VPN app and restart your iPhone. Anti-Virus software can cause the same connectivity issues and are absolutely worthless on an iPhone, so if you have one, get rid of it as well.
We assume that you have already tried the "standard" checks.
What did the tech at the Apple Store / Genius Bar say when you took your phone in to be tested?
My iPhone often will not connect to WiFi
